You could not get much better than Cambridge veterinary group (on Cherry Hinton Rd 01223 249331). the rabbit specialists are Ian Cope and Jill Pearson.
Iam has a specialist exotics cert/diploma and also does surgery, Jill has a lifetimes experience and knowledge and also does specialist skeletal and accupuncture etc.
They also have access to on-site x-rays, scanning, and various other diagnostics tools - and off site MRI/CT scans etc
Ian also has contacts to various exotics specialists.
They also benefit from excellent nurses many of whom have knowledge/experience acquired by working with Jill for many years and also with Mrs Ford, a superb rabbit surgeon who used to be with them until this year.
PS You say you havent used a vets yet for your buns - may I ask if they are up to date with their myxi and vhd vaccines? Cambridgeshire is a very high risk myxi area.